1. Field of the Invention
The present invention relates to a recording sheet used for an ink jet printer for printing monochrome and full color images at a high speed by discharging fine droplets of water-color ink, oil-based ink or the like from a nozzle.
2. Description of Related Art
Although examples of recording methods include a heat melting method, a sublimation method, an electrophotographic method, an ink jet method and the like, the ink jet recording method has recently been popularized because of its silence during recording, property of high-speed recording, ease of color recording, suitability for recording a large image and so on.
Quality requirements for such an ink jet recording sheet are the following:
(1) Having excellent ink absorptivity and producing no bleeding and the like.
(2) Having excellent smoothness and glossiness.
(3) Having water resistance and producing an image having water resistance and no bleeding and flowing-out even if moisture adheres thereto.
(4) Producing no sagging even if the sheet absorbs a large quantity of ink.
(5) Producing an image having an excellent color density and sharpness. Various improved techniques have previously been developed for satisfying the above quality requirements.
When an image formed by ink jet recording is displayed outdoors by a back light method, generally, a plastic film is laminated on the print surface thereof, or a water-resisting coating is provided on the surface because the unprocessed or untreated image cannot satisfy the water resistance of the above quality requirement (3). There is also the problem that much trouble is required for bonding another support material such as paper or the like, which has a high level of opacity, to the rear side of an image in order to improve the color density and sharpness thereof described in the quality requirement (5). In this case, the opacity is 60% or more, preferably 80% or more.